In laying out dimensions on metals or other materials in preparation for drilling, machining or other fabrication operations, the initial sheet or block of the material is typically set on edge on a plane surface or base plate. Dimensions related to the edge resting on the base plate are then measured as elevations above the surface using a form of gauge that is designed for use in this manner.
In the performance of work with instruments of this character the dimensions given on the drawing are not always taken from a single point, but are frequently marked between successive points in the structure. Consequently, if the operator is working with his gauge from a single plane it is necessary to make a mental calculation in the laying out of a dimension which is not taken from this plane. Gauges have been provided with sliding scales so that after laying out one dimension the scale may be shifted with its zero marking at a different point to lay out another dimension. However, in successively shifting the scale slight errors in adjustment occur so that some of the markings may be inaccurate.
U.S. Pat. No. 2,412,870 discloses a gauge construction employing a movable scale resulting in improved accuracy in terms of scale adjustment. This instrument incorporates a means for extending its use beyond the adjustment limitations of the gauge per se. While this instrument meets the intended objects of this invention, it leaves room for improvements in the making of fine vernier adjustments of the scale portion. The present invention also discloses a means for making such fine, accurate vernier adjustments without difficulty.